Background Since the campaign of vaccination against COVID‐19 was started, a wide variety of cutaneous adverse effects after vaccination has been documented worldwide. Varicella zoster virus (VZV) reactivation was reportedly the most frequent cutaneous reaction in men after administration of mRNA COVID‐19 vaccines, especially BNT162b2. Aims A patient, who had persistent skin lesions after BNT162b2 vaccination for such a long duration over 3 months, was investigated for VZV virus and any involvement of vaccine‐derived spike protein. Materials & Methods Immunohistochemistry for detection of VZV virus and the spike protein encoded by mRNA COVID‐19 vaccine. PCR analysis for VZV virus. Results The diagnosis of VZV infection was made for these lesions using PCR analyses and immunohistochemistry. Strikingly, the vaccine‐encoded spike protein of the COVID‐19 virus was expressed in the vesicular keratinocytes and endothelial cells in the dermis. Discussion mRNA COVID‐19 vaccination might induce persistent VZV reactivation through perturbing the immune system, although it remained elusive whether the expressed spike protein played a pathogenic role. Conclusion We presented a case of persistent VZV infection following mRNA COVID‐19 vaccination and the presence of spike protein in the affected skin. Further vigilance of the vaccine side effect and investigation for the role of SP is warranted.

Immune checkpoint inhibitors (ICI), including monoclonal antibodies to programmed death 1, programmed death ligand 1, and cytotoxic T lymphocyte‐associated antigen 4, have provided great therapeutic benefits for cancer patients at advanced stages. However, the introduction of ICI frequently results in the development of immune‐related adverse events (irAE) through activation of autoreactive T cells. Here, we present three cases of cancer patients with cutaneous irAE, including development of de novo psoriasis and exacerbation of pre‐existing psoriasis. Interestingly, these patients shared an altered histological feature characterized by loss of epidermal CD1a+ cells, namely Langerhans cells (LC), in the psoriasiform lesions in contrast to “conventional psoriasis” exhibiting unchanged or activated LC. A possible underlying mechanism was that ICI‐mediated hyperactivation of effector T cells contributed to aggravation or establishment of psoriasis phenotype, which might be associated with direct cytotoxicity or expulsion of LC from the epidermis.

Here, we report an 86‐year‐old Japanese woman presenting with confluent maculopapular erythema, which developed following the second dose of COVID‐19 Messenger RNA (mRNA) vaccine (BNT162b2). Her skin lesions spread over time and persisted for more than 3 months. Surprisingly, immunohistochemical staining of the lesion 100 days after the disease onset revealed the COVID‐19 spike protein expressed by vascular endothelial cells and eccrine glands in the deep dermis. As she had no episode of COVID‐19 infection, it is highly likely that the spike protein was derived from the mRNA vaccine and it might be the cause of the development and persistence of her skin lesions. Her symptoms were prolonged and intractable until oral prednisolone was given.